The darkest, toughest and most explicit awards contender of the year came to the AFI Fest on Wednesday night.

And after getting a look at “Shame” on the huge screen at Grauman’s Chinese Theater, guests and festivalgoers were left shaking their heads at the grim mastery of director Steve McQueen’s tale of sex addiction.

It also left them wondering about the commercial prospects for a work so unflinching.

“I’ll be going to therapy now,” laughed “Anvil!” director Sacha Gervasi as he walked through the Chinese lobby after watching Michael Fassbender’s character descend into a nightmarish dead end of empty relationships and frantic sex.

“Shame” has gotten most of its attention for its abundant sex scenes and its full-frontal nudity, mostly from Fassbender but also from co-star Carey Mulligan and a variety of others.

The film was rated NC-17 by the Motion Picture Assn. of America, just as distributor Fox Searchlight knew it would be when they picked it up this fall. But the studio is launching a full awards campaign and hoping to give the essentially moribund rating a shot of life – something that needs to be done, National Assn. of Theater Owners president John Fithian told TheWrap after the AFI screening.

“It would have destroyed this film to cut it down to an R rating,” said Fithian. “Too many filmmakers and too many studios do that, and I applaud Steve McQueen (at right with Fassbender at the AFI Fest) and Fox Searchlight for sticking to their guns.

“This is the kind of film that the NC-17 is designed for, and I think we need more bold filmmakers and distributors to make content appropriate for the rating and release it that way.”

The trouble, Fithian admitted, is that the rating has a stigma left over from the days when X, which used to be the most restrictive rating, was claimed by the porn industry. “The MPAA and NATO screwed up – we didn’t get the X rating copyrighted, and the pornographers stole it,” he said. “That shadow lingers, and so do myths about the NC-17.”

The first myth, he said, is that theaters will not play movies with the rating.

“That’s just not true,” he said. “We’ve surveyed 100 of our members, and three of them said they would never play NC17s, just as a personal choice. So that myth is 97 percent false.

And the other myth is that you can’t advertise movies that are rated NC-17. That’s wrong, too. Fox Searchlight released a Bertolucci picture a while back called ‘The Dreamers,’ and [company president] Steve Gilula says they got it played where they wanted to get it played. In terms of advertising, one newspaper in Utah wouldn’t take advertising for NC-17, and that was about it.”

Of course, “The Dreamers” was a full nine years ago, and its total U.S. gross was barely more than $2.5 million. Since then, serious adult films have either been edited to get an R rating, or they’ve been released unrated by companies who are not MPAA signatories.

For “Shame” to turn things around and serve as the leader in the revival of the NC-17, the brilliant but chilly movie will have to generate a very large snowball effect.

“We’ve had conversations with other companies encouraging them to take this kind of chance,” Fithian said. “We’ve had conversations with filmmakers encouraging them to take this kind of chance. And it takes a serious picture working, hopefully like this picture will, to get others to follow the lead.”